The activities of many people are greatly restricted owing to afflictions directly and even indirectly associated with improper footwear and certain imperfections in the skeletal and muscular complex of the foot and leg. These can cause severe foot and leg fatigue, arch strain, tendonitis, callouses, bunions, as well as knee, lower back and neck pain. If the skeletal leg and foot elements are in proper alignment the person enjoys superior control during both pronation and supination phases of the locomotion or gait cycle.
Under normal and proper physiological conditions during step-down, the foot and leg pronate inwardly through a limited arc transversely of the body whereas during pushoff the foot and leg supinate outwardly through a similar reverse arc. During pronation of the normal foot and leg, the heel and hip rolls inwardly as the forward half of the foot pivots generally about an axis offset inwardly from the inner or medial lateral edge of the foot. Pronation occurs as the heel strikes the ground and applies sufficient pressure to the rear inner corner of the heel which acts to unlock the foot complex from its relatively inflexible condition and rendering it very flexible and effective to absorb shock and stability during step-down.
During the pushoff phase of locomotion the foot and leg rolls in the reverse direction and this is known as supination. At this time the foot complex resumes its relatively rigid inflexible condition thereby enabling one to push forwardly firmly with the entire foot.
Many persons are afflicted with misaligned leg and foot complexes wherein the leg bones do not lie in a generally vertical plane. In consequence, pronation and supination do not occur normally with the result that the foot complex does not unlock and relock in the proper sequence essential for maximum ease, comfort and effectiveness of locomotion. Proposals have been made for utilizing a varus wedge at the inner rear corner of the heel to compensate for misalignment conditions but, these are frequently inadequate and ineffective to unlock the foot complex timely during step-down and mid-stance or to restore this complex to controlled relocked stable condition during pushoff. In consequence the victim is subject to some or many afflictions and discomforts including bunions, callouses leg fatigue, knee pain, hammer toes, low back and neck pain, etc.
Contributing to these afflictions in many instances is the absense in prior footwear of appropriate provisions to facilitate and reduce the resistance to the small natural outward torquing of the foot and knee known as supination and associated with the pushoff phase of gait.
Other shortcomings of prior art footwear are the lack of provision to facilitate stabilization of the foot complex together with simple self-adjusting strapping for holding the footwear to the foot alone or in combination with an insole of material effective to take a generally permanent set in conformity with the juxtaposed plantar areas in load bearing contact therewith or supplemented with means for aiding the support of the metatarsal and toecrest arches.
In recognition of the need of a large segment of mankind for more appropriate and beneficial footwear, many proposals have been made heretofore for footwear designed to alleviate physiological conditions and discomforts associated with the feet and locomotion. Examples of these include the teachings of such United States patents as: Yates U.S. Pat. No. 2,642,677, Scholl U.S. Pat. No. 3,323,233, Fukuoka U.S. Pat. No. 3,468,040, Miyachi et al U.S. Pat. No. 3,675,346, Stafford U.S. Pat. No. 3,707,784, Scrima U.S. Pat. No. 3,825,017, Jackson U.S. Pat. No. 3,968,577 and Krug et al U.S. Pat. No. 4,130,948. Although individual features of these prior proposals have been helpful to a degree they have many shortcomings and fall far short of the needs of many people. In particular, these prior teachings fail to take into account the many interrelated physical aspects of locomotion especially when associated with misalignment conditions and the shock stresses generated at step-down and the functional needs during pushoff.